Added support for Cryptex (RFC 9335)

This is final part of Cryptex (RFC 9335) implementation for pion/webrtc.
Public API is based on WebRTC Extensions specification (W3C Editor's
Draft from 19 December 2025).

Author: sirzooro

configuration.go

@@ -52,4 +52,8 @@ type Configuration struct {
 	// SDPSemantics controls the type of SDP offers accepted by and
 	// SDP answers generated by the PeerConnection.
 	SDPSemantics SDPSemantics `json:"sdpSemantics,omitempty"`
+
+	// RTPHeaderEncryptionPolicy affects whether RTP header extension encryption
+	// (RFC 9335 Cryptex) is negotiated.
+	RTPHeaderEncryptionPolicy RTPHeaderEncryptionPolicy `json:"rtpHeaderEncryptionPolicy,omitempty"`
 }